Structure of Dna

Structure of DNA

Structure of DNA

One of the most fascinating discoveries in a living thing is deoxyribonucleic acid (DNA). In this paper DNA structure and how it relates to Gregor Mendel’s inheritance patterns will be described. This paper will discuss the structure of DNA and examine how meiosis allows DNA to be divided into gametes. An understanding of the structure of DNA and a brief understanding of how DNA works lay ahead.

DNA is a chemical found in the nucleus of eukaryotic cells. DNA is a polymer. The monomer units of DNA are nucleotides, and the polymer is known as a "polynucleotide." Each nucleotide consists of a 5-carbon sugar (deoxyribose), a nitrogen containing base attached to the sugar, and a phosphate group (Access Excellence, 2011). DNA is best describes as a double helical structure. The backbone of the double helix is composed of sugar and phosphate. Each polynucleotide appears as a ribbon with nitrogenous strands. Strands that connect the double helix are composed of four nucleotides, adenine (A) with thymine (T) and guanine (G) with cytosine (C). The four nucleotides differ only in their nitrogenous base (Access Excellence, 2011). The arrangement of the strands will always be (A) to (T) or (G) to (C) (Simon, Reece, & Dickey, 2010). The polynucleotide may inverse to (T) to (A) or (C) to (G) also. Adenine and thymine are connected by two hydrogen bonds (non-covalent) while guanine and cytosine are connected by three. The double helical structure is very long making them unique from person to person. This structure was first described by James Watson and Francis Crick in 1953.

DNA composes the chromosomes and genes passed to offspring of the organism. DNA serves as the basis for inheritance because it contains all of the regenerating genes and chromosomes. The first strand of DNA will merge with the second strand of DNA either maternal or paternal to form an offspring organism. The two DNA will combine to create its very own unique strand with similarities from each creator DNA. DNA holds the genetic information of an organism. It was understood by scientists in the 1930s that chromosomes held the genes that passed to offspring. It was not until the 1960s that the DNA code was cracked and was shown to be the basis of chromosomes and genes.

Meiosis is the special cell division for sexual reproduction. This cell division differs from mitosis in that it is dealing with sexual reproduction rather that basic cell reproduction. Meiosis allows DNA to be divided into gametes by splitting one parent strand of DNA into two daughter lengths of DNA that will produce two identical strands of DNA (Access Excellence, 2011). The split begins at specific sites on the double helix, called origins of replication. The replication begins in both directions, creating what are called replication